Finally, tried this app but I'm not getting consistent results with it. Using a uca202 sound card and get consistent repeatable results in rew and holmimpulse. However, with this app one second it's showing +/- 1ms on my 20-80hz and the next it's showing a +5ms smear over a portion of the same range.

Finally, tried this app but I'm not getting consistent results with it. Using a uca202 sound card and get consistent repeatable results in rew and holmimpulse. However, with this app one second it's showing +/- 1ms on my 20-80hz and the next it's showing a +5ms smear over a portion of the same range.

Are you staying in the car for the measurement? If so, try sticking mic into the headrest and take some measurements without being in the car. Hanatsu has mentioned that measuring while sitting in the car will cause inconsistent measurements.

I have the mic clamped in the headrest roughly where the center of my head would be. I am sitting in the back seat of my crew cab. That's mainly because I don't have a long enough cable to run the laptop outside the truck.

So I'll have to say I'm impressed with the stage and coherence. From history with the tune I expected the sub to be all kinds of crazy out of phase and didn't really know what to expect. I'd have to say I'm a believer. Though was unable to get any better than the above plot. I think a lot of the troubles are simply modal and reflection related. And it does really come down to mic placement.

Looking good. I would be curious to see how your sub delay would change by using a 2nd order butterworth.

Hmm interesting. I'll try it when I get a chance. Yeah it's hard to tell what "good" should look like since we know there's so much destructive phase craziness in car. I could only tweak, measure, tweak and see if it improves or not. I guess it's a completely trial and error iterative thing.

And isn't it strange my temporary sub is literally in the back seat, though by all accounts measuring it acts like it's in the car behind me. Is it the crossover doing this?

From the practical point of view and based on psychoacoustics: 1-2ms should be just fine. For tweeters the magnitude (volume of the sound) is more important, but keeping them also within the abovementioned band will not spoil the sound stage .

It is more critical with the low end, where sub enclosures have their own generic delays: Sealed is the best, 6th bandpass - worst. Typical delay of a vented port box - 20-30ms - just to mention one. TA left/right channels might not feet 100% with the subwoofer, so it is a compromise, as always.

Using that idea for the sub visualized in this thread helped me get much better integration. In my setup the sub is only 40" away which is roughly the same length as the left mid.

I was always testing 0+ ms. After seeing the results here I tested the other way and started at 0 and delayed everything else. I had 12ms left that I could use and after doing a lot of testing I found -8.5ms measured the best in REW. I sat there and measured 1ms at a time and each measurement showed a pretty significant change in the 70-100hz range where the subs/mids integrate.

Using that idea for the sub visualized in this thread helped me get much better integration. In my setup the sub is only 40" away which is roughly the same length as the left mid.

I was always testing 0+ ms. After seeing the results here I tested the other way and started at 0 and delayed everything else. I had 12ms left that I could use and after doing a lot of testing I found -8.5ms measured the best in REW. I sat there and measured 1ms at a time and each measurement showed a pretty significant change in the 70-100hz range where the subs/mids integrate.

Quote:

Originally Posted by Alextaastrup

From the practical point of view and based on psychoacoustics: 1-2ms should be just fine. For tweeters the magnitude (volume of the sound) is more important, but keeping them also within the abovementioned band will not spoil the sound stage .

It is more critical with the low end, where sub enclosures have their own generic delays: Sealed is the best, 6th bandpass - worst. Typical delay of a vented port box - 20-30ms - just to mention one. TA left/right channels might not feet 100% with the subwoofer, so it is a compromise, as always.

Folks will say TA in bass region isn't very important, and phase is everything. I dissagree.. I believe doing this little exercise did something quite special in the bass region. I guess "coherence" is the best term I can come up with, but a kick drum is awesome. It's not bloated or undefined. I should clarify in-phase AND time-aligned = very cool!

Can't wait to do this with the two IB12AU's.

Strangely though, I couldn't do much at all about that 50hz and below so do I assume that's modal and un-fixable or rather group delay related with the sub itself?

This is the best I have been able to achieve. But as you can see my sub is 20+ ms out and I am out of delay on my tweeters. The Helix only goes to 15.6ms. So any suggestions on what I should try?
Right now I using LR 24's for all crossovers. Should I try using a lower order crossover and maybe Bessel or Butterworth instead of LR?

[IMG][/IMG]

Quote:

Originally Posted by Hanatsu

Acoustic crossovers are what matters, see the crossovers in your DSP as response shaping. There seem to be sub/mid integration issues as well as T/A and/or L/R FR inconsistancies. I would do individual measurements on all driver by RTA/noise so you get as much averaging as possible. Then compare all the individual measurements to a full left side+sub and a full right side +sub, check if all drivers sum at crossovers. Check actual slopes. Do a sweep of left side and one of the right side in RoomEQ for example, check excess group delay for large peaks which indicates destructive interference.

If the L/R EQ is set correctly you should be able to set T/A by ear very easy with correlated pink noise. I can measure my car tomorrow and show you why some of these issues occur.

Sent from my iPhone 6 using Tapatalk.

Quote:

Originally Posted by brumledb

Ok, sounds like I just need to start back at step one. I want to change my house curve anyways. I will go back and make sure I have everything dialed with with EQ before trying to utilize TDA.

brumledb, How'd this work out? You mention "back to formula".. Definitely I'd agree individual driver plots to assess "balance", and I'd encourage don't be afraid to split up your crossover points in the Helix between left/right sides if need be. My mid low-pass's are 1734 and 2244hz for example. Strikingly different electrical xo points, but they match acoustically. Two goals.. 1. Have their up-slopes and downslopes matching. 2. Individual driver EQ and levels matching between left/right sides. You want left and right individual plots approaching the impossible, being both looking like one line on top of each other.

This is the best I have been able to achieve. But as you can see my sub is 20+ ms out and I am out of delay on my tweeters. The Helix only goes to 15.6ms. So any suggestions on what I should try?
Right now I using LR 24's for all crossovers. Should I try using a lower order crossover and maybe Bessel or Butterworth instead of LR?

[IMG][/IMG]

Quote:

Originally Posted by Hanatsu

Acoustic crossovers are what matters, see the crossovers in your DSP as response shaping. There seem to be sub/mid integration issues as well as T/A and/or L/R FR inconsistancies. I would do individual measurements on all driver by RTA/noise so you get as much averaging as possible. Then compare all the individual measurements to a full left side+sub and a full right side +sub, check if all drivers sum at crossovers. Check actual slopes. Do a sweep of left side and one of the right side in RoomEQ for example, check excess group delay for large peaks which indicates destructive interference.

If the L/R EQ is set correctly you should be able to set T/A by ear very easy with correlated pink noise. I can measure my car tomorrow and show you why some of these issues occur.

Sent from my iPhone 6 using Tapatalk.

Quote:

Originally Posted by brumledb

Ok, sounds like I just need to start back at step one. I want to change my house curve anyways. I will go back and make sure I have everything dialed with with EQ before trying to utilize TDA.

brumledb, How'd this work out? You mention "back to formula".. Definitely I'd agree individual driver plots to assess "balance", and I'd encourage don't be afraid to split up your crossover points in the Helix between left/right sides if need be. My mid low-pass's are 1734 and 2244hz for example. Strikingly different electrical xo points, but they match acoustically. Two goals.. 1. Have their up-slopes and downslopes matching. 2. Individual driver EQ and levels matching between left/right sides. You want left and right individual plots approaching the impossible, being both looking like one line on top of each other. Looks like most of your issues is in the region of those 10F's. Mute the sub and forget about it for a while, until you make the scans and GZ front-stage line up like little ducks.

Caveat.. I really barely know enough about this to be a danger to myself and everyone around me. LOL!

Unfortunately I haven't had time to do any tuning since posting that. Mainly because I can't tune a little at a time, usually when I start I spend hours on it. I did do a little by ear just to get the stage centered. It doesn't sound horrible right now. The bass has a good impact up-front.
About the cross-overs, until recently I thought just set it and forget it with LR4. I didn't consider that different slopes or roll-off points should be used to electrically alter the speakers response to acoustically match whatever cross-over slope you want to attain. I have been doing a good amount of reading about cross-overs lately so now I understand this a lot better. I should be able to get some tuning in later this week, so hopefully I'll have some new and better graphs to post.

Unfortunately I haven't had time to do any tuning since posting that. Mainly because I can't tune a little at a time, usually when I start I spend hours on it. I did do a little by ear just to get the stage centered. It doesn't sound horrible right now. The bass has a good impact up-front.
About the cross-overs, until recently I thought just set it and forget it with LR4. I didn't consider that different slopes or roll-off points should be used to electrically alter the speakers response to acoustically match whatever cross-over slope you want to attain. I have been doing a good amount of reading about cross-overs lately so now I understand this a lot better. I should be able to get some tuning in later this week, so hopefully I'll have some new and better graphs to post.

Sent from my iPhone using Tapatalk

First thing I'd do is forget everything else and just do individual plots on your mids and make those corrections to get their individual plots looking more identical in REW. Then go at TDA again with their timing in mind and an idea of their distance differences.

After adjusting L/R separatelly i tried to make a combined test with both channels playing. And got some nulls and cancellations. So it became nesessary to make further improvements. It should work for you also with the help of TDA.

First thing I'd do is forget everything else and just do individual plots on your mids and make those corrections to get their individual plots looking more identical in REW. Then go at TDA again with their timing in mind and an idea of their distance differences.

Yeah, I am starting back at square one. I am going to focus on making sure I have everything dialed in with REW before trying to utilize TDA again.

I'll probably post over in the REW dump thread once I get to work on it. Try to get some opinions and make sure everything is copacetic before proceeding further. I may be going to the big SQ show at College Station in June, so I have to get a good tune in, lest I be embarrassed to demo my truck.

I'll have to check a full system rta when I get a chance. Usually, I can get 1.5k-20k for both channels to overlap with very nice accuracy. But after I go through and balance for center imaging stuff doesn't look so nice anymore. I'm curious how they're combining overall. I hate not having a peq for the mids though.

Register Now

In order to be able to post messages on the Car Audio | DiyMobileAudio.com | Car Stereo Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:

Password

Please enter a password for your user account. Note that passwords are case-sensitive.